In general a head drum comprises a fixed lower drum and a rotating upper drum, carrying at least two read/write heads in a 180° configuration on its periphery. In operation, a magnetic tape is in contact with at least half of the circumference of the head drum. For the sake of simplicity in the following, the read/write heads will be referred to only as video heads reading signals from the tape. However, it is to be noted that the invention is not limited to reading video signals.
The rotating video heads read signals from the magnetic tape, which have to be transferred to the fixed lower drum, which is connected to signal processing circuitry. It is known to use brushes to transfer the signals between the rotating upper drum and the fixed lower drum. However, in practice the transferred signals are weak and the noise generated by the brushes tends to deteriorate the transferred signals. Furthermore, brushes are not reliable over long periods of time. Therefore, rotary transformers comprising a fixed stator and a rotating rotor are utilized to transmit signals from the rotating upper drum to the fixed lower drum are utilized in today's head drums. In today's head drums the parts of the rotary transformer are fixed either by mechanical means like screws or they are fixed by glue or cement. The first solution requires additional elements and machining of the members to be connected. The second solution needs the handling of potentially hazardous products, e.g. fire hazardous glue. In addition this kind of products usually present problems to the environment.